Two-piece metal punch construction and method for making

ABSTRACT

A method and apparatus for providing an improved two-piece punch construction. The two-piece punch construction includes a supporting member and a punch body. The supporting member includes an aperture in which the punch body is accurately located. The supporting member further includes a supporting surface for supporting the punch body during a punching operation. The punch is constructed by providing at least one through-hole in the supporting member which receives a WEDM wire. The aperture for locating the punch body in the supporting member is made with a WEDM process. The supporting member and punch body are secured together by brazing material.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to the construction of a metalpunch, and, more particularly, to the construction of a two-piece metalpunch.

[0003] 2. Description of the Related Art

[0004] A metal punch is traditionally made as a one-piece construction.The one-piece construction is typically made of a single piece ofcarbide. The punch is produced from a carbide preform whereby the roughshape of the punch is established in a pre-sintered state. The head,thickness dimensions, shank diameter (if of a shanked design), and thepunch contour are finish ground. This method of creating a one-piecepunch, however, is expensive and time-consuming. While this structurehas the advantages of rigidity and strength, the material and labornecessary to produce a one-piece carbide punch cause such punches to beexpensive.

[0005] A two-piece punch construction is an alternative to a one-piececonstruction. A common two-piece punch construction, however, onlyovercomes one problematic aspect of a one-piece construction. The commontwo-piece punch construction, while less time-consuming and expensive tomake, is not as strong and rigid as the one-piece punch construction. Ina two-piece punch construction, the punch body is made in the form of a“stick” by using wire electrical discharge machining (WEDM) of arectangular stock block of carbide. Alternatively, the punch body ismade by the grinding of a headless carbide preform. The head is made ofsteel. The cross-sectional shape of the punch body may be WEDM-cutthrough the head. The head and punch body are joined by fillet brazing.This construction, however, raises problems. First, the two materialswill often separate because the punch head is not supported by aperfectly flush substrate. Frequently, the punch head is supported by asetscrew the lower surface of which is cup-shaped. Even when the lowersurface of the setscrew is ground flat, the setscrew may not provideeven contact with the punch head. If the setscrew, or other support,comes in contact with the steel head but not the carbide portion of thepunch, the impact of the punching operation will tend to shear the brazeand separate the head and the punch body.

[0006] What is needed is a punch construction which provides thestrength and rigidity of the one-piece punch construction without thecost and time problems associated therewith. What is further needed is apunch construction which provides the cost and time benefits of thecommon two-piece punch construction without the loss of strength andrigidity.

SUMMARY OF THE INVENTION

[0007] The present invention provides a two-piece punch constructionwhich maintains the integrity of a one-piece punch construction whileproviding the cost and time advantages of a two-piece punchconstruction.

[0008] The present invention, in one form thereof, comprises a two-piecepunch construction including a head (or head and shank combination) anda punch body, and a method for making. The head or head and shankcombination hold the punch body and include an aperture in which thepunch body is accurately located. The head or shank includes asupporting surface for the punch body. The head or head and shank aremanufactured with at least one through-hole which is operable to receivea wire used in a WEDM process. The WEDM process creates the accurateaperture in the head in which the punch body is located.

[0009] An advantage of the present invention is that the punch accordingto the invention is less expensive than prior art punches.

[0010] Another advantage of the present invention is that the two-piecepunch according to the invention is as strong and rigid as a prior artpunch constructed of a single piece of material.

[0011] Yet another advantage of the present invention is that thetwo-piece punch according to the invention is considerably stronger thanprior art two-piece punch constructions.

[0012] A still further advantage of the present invention is thereduction of production time to produce a punch according to theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above-mentioned and other features and advantages of thisinvention, and the manner of attaining them, will become more apparentand the invention itself will be better understood by reference to thefollowing description of an embodiment of the invention taken inconjunction with the accompanying drawings, wherein:

[0014]FIG. 1 is a prior art one-piece shanked punch construction.

[0015]FIG. 2 is a bottom view of a punch head before WEDM according tothe present invention.

[0016]FIG. 3 is a cross-sectional view of the head taken along line 3-3of FIG. 2.

[0017]FIG. 4 is a cross-sectional view of the head of FIG. 2 duringWEDM.

[0018]FIG. 5 is a top view of the head after WEDM according to thepresent invention.

[0019]FIG. 6 is a top view of the punch of FIG. 7.

[0020]FIG. 7 is an exploded view of a two-piece shanked punch accordingto the present invention.

[0021]FIG. 8 is a cross-sectional view of the punch of FIG. 7 takenalong line 8-8.

[0022]FIG. 9 is a cross-sectional view of the punch of FIG. 7 takenalong line 9-9.

[0023]FIG. 10 is a side view of a two-piece shanked punch according tothe present invention.

[0024]FIG. 11 is a top view of a head with three apertures after WEDMaccording to an alternative embodiment of the present invention.

[0025]FIG. 12 is a top view of a head with four apertures after WEDMaccording to an alternative embodiment of the present invention.

[0026]FIG. 13 is a top view of a head with two apertures after WEDMaccording to an alternative embodiment of the present invention.

[0027]FIG. 14 is an elevational view of a shankless punch according tothe present invention.

[0028] Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate preferred embodiments of the invention, in one form, and suchexemplifications are not to be construed as limiting the scope of theinvention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

[0029] Referring now to the drawings and particularly to FIG. 1, thereis shown a prior art one-piece shanked punch construction. One-piecepunch 100 is traditionally made of a single piece of carbide. Punch 100is produced from a carbide preform which provides the rough shape ofpunch 100 in a pre-sintered state. Punch 100 is then finish ground. Thegrinding process defmes head 102, shank 103, punch body 106, and punchsurface 104. Head 102 represents the part of the punch which is held bythe upper die (punch) assembly in a press. Punch surface 104 providesthe punch surface which contacts the sheet metal or other material to bepunched in a punching operation. The materials and labor associated withthe production of punch 100 are expensive. Furthermore, the process tomanufacture punch 100 is time consuming and may take up to forty-fivedays, including delivery time of the carbide preform from the carbidemanufacturer.

[0030] In accordance with the present invention, FIG. 7 illustrates anunassembled exploded view of a two-piece shanked punch construction.Two-piece punch 300 includes punch body 308, head 200 and shank 203.Punch body 308 may have any shape which will accommodate specificmanufacturing capabilities and design requirements. Punch body 308 isoperable to be accurately and securely placed into shank 203, and, morespecifically, into aperture 216. Punch body 308 must be inserted intoaperture 216 with a close fit, e.g., a line fit, whereby punch body 308cannot move laterally. Punch body 308 includes punch surface 302 whichprovides the working surface of the punch and which contacts the sheetmetal or other material to be punched in a punching operation. Punchsurface 302 also defines a transverse cross-section for punch body 308.Punch body 308 may have a uniform cross-section throughout the length ofpunch body 308. The cross-section is shown as “kidney” shaped. Punchbody 308, however, could be contoured at the end which is inserted intoaperture 216 to better locate punch body 308 in shank 203 in certainapplications. Punch body 308 further includes bottom surface 304 whichprovides a surface to contact a portion of shank 203 to be described indetail below. Recess 306 is provided in the side of punch body 308 topromote better locking of punch 300 in head 200. Such a locking element306 could also be a notch, a projection, or any other suitableconfiguration which is advantageous to particular manufacturingcapabilities and design requirements.

[0031] Punches can be manufactured with a shanked construction, toinclude a head 200, shank 203 and a punch body 308. Alternatively, theshankless punch could be constructed to have a head 200 and a punch body308. FIG. 7 illustrates a shanked construction of a punch 300. Bycontrast FIG. 2 illustrates a head for a shankless punch.

[0032] In the configuration of FIGS. 2 and 7 the head is shown ascylindrical in shape. Alternative shapes of heads could also be used.

[0033] In order to provide an aperture 216 as shown in FIG. 7, a WEDMprocess may be used to manufacture the very accurate aperture 216 asfurther explained hereinbelow. While WEDM is a preferred method forproviding aperture 216, it is possible that other methods of removingmetal to make the very accurate aperture 216 could also be used.

[0034]FIG. 2 illustrates a top view (i.e., looking from surface 104toward the head) of head 200 of a shankless punch before WEDM. Head 200may be made of steel or any other suitable material which is strong,easily manufactured, and inexpensive. Head 200 must be able to holdpunch body 308 as well as be suitable to be held by the upper die(punch) assembly used in a punching operation. Head 200 must be largeenough in diameter to more than circumscribe punch body 308. Head 200must include a through-hole 202 to accommodate a WEDM wire. Counterbore205 in head 200 has an outer peripheral surface 204 defining theperimeter of counterbore 205. Counterbore 205 further defines supportingsurface 212. Supporting surface 212 must be present in head 200 foradequately supporting punch body 308. Counterbore 205 is formed usingany suitable method including turning, milling, EDM, drilling, andbroaching and must be large enough to provide an adequate supportingsurface 212 for punch body 308. Counterbore 205 need not be as accurateas aperture 216 since the WEDM process accurately locates the punch.Head 200 includes outer surface 206 which defines the outside perimeterof head 200.

[0035]FIG. 3 illustrates a cross-sectional view of head 200 before WEDMtaken along line 3-3 of FIG. 2. Head 200 includes outer surface 206,bottom surface 208, and top surface 210 thereby defining the outsidedimensions of head 200. Through-hole 202 is provided in head 200 toprovide a location for WEDM wire 214. Counterbore 205 provides forsupporting surface 212 which is operable to support punch body 308during a punching operation.

[0036]FIG. 4 illustrates a cross-sectional view of head 200 during WEDMtaken along line 3-3 of FIG. 2 with WEDM wire 214 located inthrough-hole 202. WEDM wire 214 extends through through-hole 202. TheWEDM process allows for the machining of apertures of any shape orvariety that will accommodate manufacturing capabilities and designrequirements.

[0037]FIG. 5 illustrates a top view of head 200 after WEDM (i.e., asseen from the end of the punch at which surface 302 is located). WEDMwire 214 provides machined aperture 216 which very accurately locatespunch body 308. Aperture 216 extends through head 200 and forms a closefit, e.g., a line fit, with punch body 308.

[0038]FIG. 6 illustrates a top view of punch 300 as seen from the end atwhich surface 302 is located. The supporting surface for punch body 308is defined by supporting surface 212. Supporting surface 212 must beadequate to fully support punch body 308 during a punching operationwithout any negative effects on the punch. Support surfaces 212 a and212 b of supporting surface 212 are shown in dashed lines. Surfaces 212a and 212 b provide the necessary support for punch body 308 and aredefined by punch body 308 and supporting surface 212. Aperture 216 ispartially drawn in dashed lines, while punch outline 207 is shown insolid lines. As indicated in this embodiment, counterbore 205 need notbe accurately machined and provides a location for a suitable securingmaterial, such as brazing material, to retain punch body 308.

[0039]FIG. 8 illustrates a cross-sectional view of shanked punch 300taken along line 8-8 in FIG. 7. Punch body 308 is located in aperture216 in head 200. Punch body 308 is secured in head 200 with securingmaterial 400. Securing material 400 secures and retains punch body 308in head 200. Suitable securing material 400 may include brazingmaterial, silver solder, adhesive, epoxy, weld, or any other suitablematerial.

[0040]FIG. 9 illustrates a cross-sectional view of punch 300 taken alongline 9-9 in FIG. 7. Punch body 308 is located in aperture 216 and issupported by supporting surface 212. Punch bottom surface 304 is atleast partially flush with supporting surface 212, thereby providing aflush substrate to support punch body 308 during a punching operation.Element 306 is operable to lock punch body 308 in head 200. Inoperation, recess 306 aids securing material 400 to facilitate theholding of punch body 308 in head 200. Element 306 could be any devicewhich aids in the rigid maintenance of punch body 308 in head 200, suchas a recess, notch, projection and the like.

[0041]FIG. 10 illustrates a side view of punch 300. Punch body 308 islocated in head 200 with punch surface 302 operable to perform apunching operation.

[0042] There are an infinite number of ways to position WEDM apertures216 to make an infinite number of punch shapes. The location ofapertures 216 and number of punch shapes are able to suit any shape orvariety that is necessary to accommodate manufacturing capabilities anddesign requirements. FIG. 11, FIG. 12, and FIG. 13 provide threeexamples of the alternate ways to position apertures 216 and shape punchbody 308.

[0043]FIG. 11 is an alternative embodiment of the present invention andshows a top view of head 200 after WEDM, i.e., as seen from the sideinto which a punch is inserted. Head 200 contains three apertures 216formed with WEDM. The outline for a punch body 308 is shown by solidline 207. Counterbore 205 provides a location for securing material 400.Apertures 216 extend through head 200 and accurately locate a punch body308. Supporting surface 212 is defined by the dashed-line portions ofapertures 216 and circular portion of outline 207. Supporting surface212 provides a support for a surface 304 of a punch body 308 during apunching operation.

[0044]FIG. 12 is an alternative embodiment of the present invention andshows a top view of head 200 after WEDM, i.e., as seen from the sideinto which a punch is inserted. Head 200 contains four apertures 216formed with WEDM with punch outline 207. Counterbore 205 provides alocation for securing material 400. Apertures 216 extend through head200 and accurately locate punch body 308. Supporting surface 212 isdefined by the dashed portions of apertures 216 and circular portion ofoutline 207. Supporting surface 212 provides a support for surface 304of punch body 308 to surface against during a punching operation.

[0045]FIG. 13 is an alternative embodiment of the present invention andshows a bottom view of head 200 after WEDM, i.e., as seen from the sideinto which a punch is inserted. Head 200 contains two apertures 216formed by WEDM with punch outline 207. Counterbore 205 provides alocation for securing material 400. Apertures 216 extend through head200 and accurately locate punch body 308. Supporting surface 212 isdefined by the dashed portions of apertures 216 and portions of outline207 within counterbore 205. Supporting surface 212 provides a supportfor surface 304 of punch body 308 to surface against during a punchingoperation.

[0046]FIG. 14 shows a shankless punch according to the present inventionwith a punch 106 and a head 102.

[0047] While this invention has been described as having a preferreddesign, the present invention can be further modified within the spiritand scope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and which fallwithin the limits of the appended claims.

What is claimed is:
 1. A punch comprising a punch body; a member forholding said punch body, said member including an aperture in which saidpunch body is located, a supporting surface for supporting said punchbody, and at least one through-hole.
 2. The punch according to claim 1wherein said member comprises a head.
 3. The punch according to claim 1wherein said member comprises a shank, said punch further including ahead connected to said shank.
 4. The punch according to claim 1 whereinsaid punch body is made of carbide material.
 5. The punch according toclaim 1 wherein said member is made of steel.
 6. The punch according toclaim 1 wherein said punch body includes a peripheral surface andwherein said aperture forms a close fit with only predetermined portionsof said peripheral surface.
 7. The punch according to claim 1 includingsecuring means for securing said punch body in said member.
 8. The punchaccording to claim 6 wherein said securing means comprises brazingmaterial.
 9. The punch according to claim 6 wherein said securing meanscomprises an adhesive.
 10. The punch according to claim 1 wherein saidmember includes a counterbore for accommodating said punch body, saidcounterbore defining said supporting surface.
 11. The punch according toclaim 9 wherein said counterbore receives securing material for securingsaid punch body in said member.
 12. The punch according to claim 10wherein said securing material is brazing material.
 13. The punchaccording to claim 1 wherein a transverse cross-section of said punchbody is uniform throughout the length of said punch body.
 14. The punchaccording to claim 1 wherein said punch body includes a lockingmechanism to lock said punch body in said member.
 15. A method formaking a punch comprising the steps of: providing a supporting member;providing a counterbore in said member, said counterbore defining asupporting surface; machining a punch aperture in said member; andlocating said punch body in said punch aperture.
 16. The methodaccording to claim 14 wherein said machining step comprises electricdischarge machining.
 17. The method according to claim 14 wherein saidmember comprises a head.
 18. The method according to claim 14 whereinsaid member comprises a shank, said punch further including a headconnected to said shank.
 19. The method according to claim 14 includingthe step of securing said punch body in said member.
 20. The methodaccording to claim 14 including the step of providing a through-hole insaid member and locating an electric discharge machining wire in saidthrough-hole.
 21. The method according to claim 15 wherein said securingstep comprises brazing.
 22. The method according to claim 14 wherein aplurality of punch apertures are provided in said member.